Conventionally, a compact disc (hereinafter referred to simply as a “CD”) or a digital versatile disc (hereinafter referred to simply as a “DVD”) is used as an optical disc, on which digital content of music data, picture data, video data having copyright is recorded, and from which such data can be reproduced using an optical playback means. An optical disc of this kind has digital content recorded thereon in a standardized recording format.
Optical discs are used as recording media, which can be mass-produced from a master disc and can be distributed widely for commercial purposes. Optical discs having the same digital content are basically of the same shape, and are housed in packages to be distributed, respectively. For the purpose of identifying so called “packaged media” each containing an independent optical disc to be distributed with common digital content, generally, a printed material having a serial number printed thereon is included in each package. In addition, a label having such serial number printed thereon is stuck to each package.
Even though each of these packaged media can identify its optical disc using a serial number attached thereto, it is impossible to identify each optical disc itself without its package. Furthermore, in the event that a label with a serial number is peeled off to be lost, or a printed material with a serial number is lost, an optical disc cannot correspond to its serial number on its label or printed material. Furthermore, in the event that an optical disc itself is transferred to anyone apart from its package, it also may become difficult to manage the optical disc using its serial number.